a two-dimensional layerpuzzle existing from 17 different pieces, all made from circles and triangularsegments; it is possible to find more than the given square-shape, also a butterfly, a big Y, a rectangular, and some more symmetrical shapes are possible to solve; the name Erbium is deduced from the elemnt Erbium which is the 68th element in the periodic system and has also a hexagonal structure in the crystals;
the 17 puzzlepieces are also made from 68 pieces

difficulty

although there are more solutions for every shape are possible it is always a difficult layer-puzzle